This invention relates to a helical gear fluid machine, such as pump or motor, of the progressive cavity type, in which, generally, a rotor of n starts is caused to rotate and orbit within the stator of n.+-.1 starts. Alternatively, it has been suggested in U.S. Pat. No. 1,892,217 to produce a pump or motor in which the stator, the outer element, rotates, rather than being fixed, and forms the outer casing of a chamber in which the rotor rotates about a fixed axis, and through which the fluid is pumped.
The casing of the chamber is supported for rotation about its axis by plates forming the inner part of the end walls of the chambers at either end of the pump, through which fluid passes, on the outside of the pump casing. In this suggestion, fluid is admitted to or from the casing through these supporting end walls, which are shown as the inlet/outlet ducts of the pump. O-rings are provided to support the thrust bearings between its supports and the casing, to allow for axial misalignment and at the entry of the drive shaft for the inner element.